We have used the velocity-map imaging (VMI) technique to measure autoionization dynamics in molecular nitrogen initiated by a train of attosecond pulses. The pump-probe measurements show clear evidence of a crossing between potential energy curves of the highly excited N2+ ion and of the N22+ ion. It is found that the autoionization becomes energetically allowed when the two nuclei are still very close (∼3 Å), in contrast with observations in other diatomic molecules, and that it can be coherently manipulated by a strong femtosecond infrared pulse.

Phys. Rev. A

Lucchini, M., Kim, K., Calegari, F., Kelkensberg, F., Siu, W., Sansone, G., … Nisoli, M. (2012). Autoionization and ultrafast relaxation dynamics of highly excited states in N2. Phys. Rev. A, 86(4, Article number: 43404), 1–4. doi:10.1103/PhysRevA.86.043404